Oleg Zabluda's blog
Tuesday, May 15, 2012
Good news, everyone. Antimatter Rocket engines seem easier then ever.
Good news, everyone. Antimatter Rocket engines seem easier then ever.

When I was ~15, I did what every 15 year old does. Take non-relativistic Tsiolkovsky rocket equation, plug in numbers for matter-antimatter annihilation, producing pure photons, all radiated directly backward, and voila - relativistic delta-v with reasonable mass fraction.

When I was ~25, and already in US, I laid my hands on the "The Starflight Handbook" https://plus.google.com/112065430692128821190/posts/X5zQr7q76sc That's when bad news hit for the first time. Turned out that those are gamma photons, emitted in pairs in all directions, can't be reflected or focused, so things are bleak. Moreover, in proton-antiproton annihilation, what mostly comes out is not light, but relativistic pions, which is less efficient in terms of momentum per mass, and can't be collimated anyhow. Oh, and antimatter can't be reasonably produced.

Now that I am ~45, finally, some good news!

First of all, LHC contributed better particle-collision simulation software, which allegedly shows that resulting charged particle beam can be sufficiently collimated using 10 Tesla magnets, technology for which was also contributed to by the LHC. New calculations increase Isp from 0.33c to 0.69c, reducing mass fraction by exp(0.69)/exp(0.33)=1.4.

Second of all, antiprotons don't actually have to be produced. They can be harvested from cosmic rays, concentrated by Jupiter's magnetic field, as was announced in Aug 2011 by the PAMELA satellite team.

And third of all, pions can be effectively stopped by Tungsten and such



"SuperMoon" schedule on May 5 2012
"SuperMoon" schedule on May 5 2012
in San Francisco went like this (all times are PDT):

Moonrise: 8:03 pm
Sunset: 8:04 pm
Perigee 8:34pm
Full Moon 8:35

Let's check is everything was OK in the Heavens:

The Moon does go around the Earth (passes the same star) every 27.3
days. This is what is called "Sidereal" month, from Latin sidereus,
which means "astral" or pertaining to stars. If this was chosen as the length of the calendar month, there would be 365.25/27.3=13.4
months in a year. The reason we don't, is because during this time,
the Sun also moves. To the first order, it takes the Moon additional
27.3/13.4 = 2.0 days to catch up with the Sun, for the total of
27.3*(1+1/13.4)=29.3 days, the correct number being is 29.5, using elementary math, or simply adding higher orders, and more
precise value of the constants),
27.3216*(1+1/13.37+1/13.37^2+1/13.37^3+1/13.37^4+...) = 29.53
This is when Moon phases repeat, and is called "Synodic" month, from Greek. synodos "assembly, meeting, conjunction of planets," from syn-
"together" + hodos "a going, a way". Note that Astronomical
"conjunction" and Church "Synod" is the same word, differing only in
gathering of heavenly bodies and human bodies respectively.

At Moonrise the Moon was 1 minute away from the point opposite to the
Sun. It should have taken 27.3 minutes for it to reach it
(8:03+0:27=8:30). But during this time, the Sun moved, so it actually
took the Moon 30 minutes to actually reach the point actually directly
opposite to the Sun (8:03+0:30=8:33). The actual time was 8:35 (due to
all the numbers being given to the closest minute). So the heavens
check out to the first approximation..

One has to check on the skies. Once I woke up at 3 am to look at the
Total Lunar Eclipse, and there wasn't any, not even partial. I was
still half-asleep, but was immediately jolted awake by the shock and
realization that something happened to the Heavens between 1am, when I went to bed and didn't hear any emergency announcements, and 3 am when the Moon missed Earth's shadow altogether. Turned out, I simply
confused the dates.

There will be more Moon posts coming in the next Synodic month.



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